How would I create a spark with the arduino? Can you hack a grill ignitor or model rocket launch controller? I'm thinking to recreate the Zeppelin blimp, but with flame retardant paper shell. I was thinking to fill with hydrogen by a foil and hydrochloric acid mix leading up to the blimp interior. Then either by a timed delay or RC control cause an internal combustion inside the blimp to see what the end result would be. what if the design works, proven a new shell material could bring back the hydrogen blimp! Can I break a small light bulb and burn the tungsten coil thru a digital pin?

billroy

It does sound quite impressive. Not for direct connection to an arduino pin, at that level of current. Search the forum and read up on driving high-current peripherals with a transistor or FET, or even a relay, which itself will require a transistor.

I was thinking to fill with hydrogen by a foil and hydrochloric acid mix leading up to the blimp interior.

If you do this, don't fill it with hydrogen in this manner. And please don't light it off. Why?

Because what you are describing is basically a kind of poisonous gas bomb; the reaction of hydrochloric acid with aluminium basically creates hydrogen and chlorine gas via an exothermic reaction (that is, the reaction gets hot - very hot). In fact, left to its own devices, with enough aluminium and a high enough concentration of HCl, it will self-ignite. It's actually a commonly known "anarchist's cookbook" type of device (though usually done in a capped-off 2 liter bottle, with a burning candle or flare on top - nothing like burning plastic shrapnel and chlorine gas to get your blood going!).

Likely, you wouldn't poison yourself, but you might make yourself sick, eye irritation (or worse), etc - such a mix is very nasty stuff...

jabbado

I agree. Although we used to fill 75 liter garbage bags using a slightly different (but just as dangerous) reaction. Everything was weighed accurately and cold water baths used to control the reaction rate. But I studied chemistry so was aware of the dangers, and what was the quickest way to the shower, and to the hospital. Still a silly thing to do.

BTW, hydrogen will ignite over a huge range of O2 concentrations. Even a few percent of oxygen could likely turn your blimp into a bomb.

oh shit that does sound dangerous just mixing the 2 items aluminum and hydrocloric acid. I've once did it ouside in a glass flash. I'm not sure if it was enough to inflate a balloon completely. I won't do that, however a gas filled blimp that exploded would be cool caught on video! the dangerous by-produce of chlorine gas I wouldn't worry about too much because the experiment would be outside and we would be plenty aware of the gas. At a higher height no one should be affected. :*

do you guys think Spark Gap ignitor create a spark hot enough to lite a medium sized bottle rocket or even a model rocket engine??? How cool would it be to have a model airplane that could shoot bottle rockets by IR control! ^_^

focalist

Electrolysis of water is a MUCH safer method to produce hydrogen.. and oxygen for that matter. Capture off the electrodes, and you can harvest nearly pure gases. Best of all, you know you have a proper mix of hydrogen and oxygen, as your source and endpoints- water- are the same. Energy stored in the chemical bonds is everything else.. In addition, it's pretty impressive once you think about it. It will take quite a while to generate a good volume of gases.. depending on setup, hours or even days. All the energy being dumped in to break the water chemical bonds over all that time... and when ignited, all that energy is released in a fraction of a second. Electrolysis and combustion is a great hands-on example for demonstrating chemical storage of energy!

That all being said, I think you need to read a few things:

"The flammability limits based on the volume percent of hydrogen in air at 14.7 psia (1 atm, 101 kPa) are 4.0 and 75.0. The flammability limits based on the volume percent of hydrogen in oxygen at 14.7 psia (1 atm, 101 kPa) are 4.0 and 94.0." "The limits of detonability of hydrogen in air are 18.3 to 59 percent by volume"[4]

http://en.wikipedia.org/wiki/Hydrogen_safety

Don't underestimate the power of the explosive you are dealing with. This is NOT a safe project-- take EXTREME care... and if you have any doubts at ALL, do not do it. You are essentially building a bomb if you try to contain detonating fuel/air vapor. Even if explosion is avoided, the flame jet (which is invisible) will ignite ANYTHING it's close to- it will be a high-powered, invisible blowtorch (gas-fueled rocket?). In either case, very dangerous.